1. Field of the Invention
This invention relates to a heated laminated glazing, in particular a laminated glazing comprising a monolithic or laminated support, of glass and/or plastic, and a transparent plastic sheet comprising at least one polyurethane layer, particularly a polyurethane layer exhibiting energy-absorbing properties.
2. Description of the Related Art
Transparent plastic sheets, able to be applied by pressure when hot to a face of a laminated glazing (support), have already been described, particularly in French patent No. 2 398 606. According to this patent, the sheet comprises two layers, one formed by a thermoplastic material exhibiting energy-absorbing properties and adhering to the surface of the support of glass or plastic and the other being formed by a thermosetting layer exhibiting antilaceration and resilience (i.e., self healing) properties.
These glazings can be used particularly as windshields or rear windows of motor vehicles or as glazings for buildings. The glazings, when used in motor vehicles, are generally attached by gluing in the window opening of the vehicles. To protect the adhesive, used to attach the glazings, from ultraviolet radiation and to make it invisible from the outside, the face of the laminated support covered by the thermoplastic layer generally carries on its periphery an enameled border, as indicated in French patent No. 2 595 983.
These glazings are conventionally not heated. The usual heated glazings are those laminated glazings with two glass plates between which are inserted a transparent plastic sheet, an electroconductive coating and power lead-in strips. These various elements are strongly held by the two glass plates.
It is advantageous to have laminated glazings with a single glass plate, as described above, particularly because these glazings provided only with a transparent plastic sheet in two layer form, i.e., comprising a layer of thermoplastic material and a layer of thermosetting material, offer advantages relative to the laminated glazings with two glass plates. One of the advantages is that the laminated glazing with a single glass plate can be given very diverse, and even complex, shapes by bending, due to the fact that a single glass plate is to be treated. In the case of laminated glazings with two glass plates, two plates must be bent and obtaining shapes perfectly fitting one another is not an easy achievement.
One of the problems posed by the heated laminated glazings with a single support is their mechanical stability, since the various intermediate elements are held by only one support, such as glass, and a plastic sheet.